Photosensitive sheets provided with photosensitive film on one side of the support include, for example, planographic printing plates used for offset printing or the like. Planographic printing plates undergo a step for separating and taking out the top sheet one at a time from the stack of planographic printing plates in a state where a plurality of sheets (for example, 100 sheets) of square planographic printing plates are stacked, by using a robot (such as sucker robot), and feeding it to next apparatus (such as exposure machine), system, or the like. During such a process to take out a planographic printing plate one at a time, problems will occur in later processes if a plurality of sheets are taken out at a time; therefore, it is important to ensure that one sheet is separated and taken out at a time from the stack of a plurality of planographic printing plates.
Based on those backgrounds, in the conventional planographic printing plates, papers called slip sheets were alternately placed with the planographic printing plates so as to facilitate the separation from each other and protect them by preventing scratches on photosensitive film due to friction between the planographic printing plates (for example, refer to Japanese Patent Application Laid-Open No. 2001-151360).
However, using slip sheets causes the cost increased, and moreover, prevents the system being compact, requiring a process for alternately placing the slip sheets with the planographic printing plates in stacking the planographic printing plates. Such photosensitive sheets that are separated and taken out one at a time from the stack thereof are not limited to planographic printing plates but also include X ray films, which also have similar problems.
Regarding the roles of slip sheets, protection and separation of photosensitive film, Japanese Patent Application Laid-Open No. 50-151136 discloses providing a soft polymer or paper debris on the support side which is opposite from the photosensitive film, thereby protecting the photosensitive film without using slip sheets when they are stacked. Also, Japanese Patent Application Laid-Open No. 61-67863 discloses providing a coat layer (for example, hydrophobic polymer compounds) having thickness of 100 μm or less on the backside of planographic printing plates having photosensitive layer, thereby preventing scratches being made on photosensitive layer due to friction between the planographic printing plates while being stacked or conveyed.